The forensic reconstruction of road traffic accidents

185 Pages·2017·5.36 MB·English

by  Caroline Fixter

The forensic reconstruction of road traffic accidents
URQUHART, Simon
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The Forensic Reconstruction of Road Traffic Accidents
Simon J. Urquhart
A thesis submitted in partial fulfilment of the requirements of
Sheffield Hallam University
For the degree of Master of Philosophy
September 2015
Abstract
This project aims to approach the issues of collision damage quantification
and accident scene reconstruction in a critical manner. A series of accident
scenarios that demonstrate modern-day vehicle collisions will be presented.
The collision damage will be studied with regard to the scene, environment
and the path and speed of each vehicle. The scientific focus will involve how
the accuracy of the process in comparison to forensic measurements made
at the scene, and how well the reconstruction process describes the features
of the incident.
The work will show how a software package tailored for traffic accident
investigators can study the impact damage resulting from a collision, plus
variables such as the speed and trajectory of the vehicles involved, to
improve the reconstruction analysis and reduce overall doubt in any
judgments.
As the use of road networks continues to expand globally, accidents are
prevalent in every country where cars and other vehicles are present. By
gaining a better understanding of how such accidents occur, the occurrence
and cost of these avoidable events may be reduced. The use of accident
modelling software is established specifically for this purpose; to provide an
unbiased platform for implementing cases from a basic parking bump to a
motorway pile-up, enabling such variable effects as weather, road surface
and the type of tyres to be accounted for.
Candidate’s Statement & Acknowledgement
Overall this thesis describes the work that has gone into determining how
well a commonly used process of accident analysis can be applied to a real-
life scenario. It is often assumed that purchase of an item of software will
provide a specific solution to a certain problem; less commonly the question
is asked as how well suited the software truly is and how adept this solution
is at meeting its designated function. This was the aim of the work presented
here.
The collaboration of Gwent Constabulary should be noted for provision,
advice and criticism at most stages of the research. The depth and scope of
material provided was given generously and without bias, and this research
would not have been possible without this help. In addition to this
acknowledgement, the following immensely useful people each deserve a
hundred cheers and a thousand beers:
PC Goddard for providing the caseload & counsel
Prof. Alan Smith for advice and police contacts
M. Roberts-Lewis for stress management
Dr. Syed Hasan for project supervision
Kate Wilicox for external support
Wilderness Systems
Scott USA Co.
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Table of Contents
1. Introduction 8
1.1 Accident Investigation 9
1.2 Commencing this Research 10
1.3 Project Objectives 11
2. Literature Review 13
2.1 An Introductory Note on Modelling systems for Vehicle Collisions 13
2.2 Momentum Model 14
2.3 CRASH Algorithm & Model 15
2.4 Crush Measurement & Quantification 19
2.5 Computer Collision Simulation 26
3. Theory, Analysis & Methodology 33
3.1 Model overview 33
3.1.1 Police RTA Case calculations 37
3.2 Methodology & Reconstruction Approach 39
4. Research Methodology & Approach 45
4.1 Obtaining a RTA Caseload 46
4.2 Meeting with Investigator & Integrating Evidence 48
4.3 Reconstruction Process From Evidence 50
4.4 Caseload of RTA Incidents 54
4.5 Example of RTA Case Evidence 55
4.6 Scenario Modelling Methodology 60
4.6.1 Mapping 60
4.6.2 Vehicle Modelling 63
4.6.3 Vehicle Setup 63
4.6.4 Vehicle Data 64
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4.6.5 Dynamics & Trajectory 70
4.6.6 Impact 74
4.7 Accuracy of Evidence 78
4.8 Integrating Investigator’s Data & Accuracy in Reconstruction 81
5. Results 83
5.1 RTA1 Collision: Car rear end shunt (example) 84
5.2 RTA2 Collision: Plymouth, Junction collision at low speed 86
5.3 RTA3 Collision: Warnham, Sussex, Collision at Junction 89
5.4 RTA4 Collision: Danbury, Essex, High-Speed Collision 93
5.5 RTA5: Usk BMW and Van High-Speed Collision, A449, Wales 98
5.6 RTA6: Usk A472, Multi-vehicle, Medium-Speed Collision 105
5.7 RTA7: M4 Coldra Junction, Medium-Speed Fatality 111
5.8 RTA8: M48 Rogliet, Head-on Collision with Emergency Barrier 116
5.9 RTA9: A48 Coedkernew, Vehicle Rollover 121
5.10 RTA10: A467 Aberbeeg, Bus and Car Collision 126
6. Discussion of Results & Professional Feedback 133
6.1 RTA1 Example 134
6.2 RTA2 Plymouth 134
6.3 RTA3 Warnham 135
6.4 RTA4 Danbury 136
6.5 RTA5 Usk A449 138
6.6 RTA6 Usk A472 140
6.7 RTA7 M4 Coldra 142
6.8 RTA8 M48 Barrier Collision 143
6.9 RTA8 Coedkernew SUV 145
6.10 RTA10 Aberbeeg 148
6.11 Summary of Investigator’s Comments 150
7. Critique 152
7.1 Investigators 152
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7.2 Capabilities of software 153
7.2.1 Vehicles 153
7.2.2 Layout and Environment 154
7.2.3 Frictional Forces 156
7.2.4 Vehicle Crush 157
7.3 Suggestions for Overcoming Software Limitations 158
7.4 3D Reconstruction 159
7.5 Suitability for Legal Proceedings 161
7.6 Suitability/Unsuitability for Court 162
8. Conclusions & Further Work 165
8.1 Project Objectives 165
8.2 Suggested Improvements 166
8.3 Future Developments 168
References 170
Appendix 174
3D Reconstruction Data 174
Project Timeline, Appointments & Visits 175
Table of Figures
Fig. 3.1: Schematic of impact model used in PC-Crash 34
Fig. 3.2: Geometric schematic of impact model showing contact plane 35
Fig. 4.1: Ordnance survey map of RTA5 area 55
Fig. 4.2: View of the impact marks of RTA5 56
Fig. 4.3: View showing the camper van’s path of RTA5 57
Fig. 4.4: View showing the later stages of the skid marks from BMW 58
Fig. 4.5: In-built road modelling 60
Fig. 4.6: Imported Google map 61
Fig. 4.7: Roadside polygons (3=barrier, 4=sign) 61
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Fig. 4.8: Roadsign and barrier polygons, 3D view 62
Fig. 4.9: Main viewport of PC-Crash 63
Fig. 4.10: Vehicle selection from database 64
Fig. 4.11: Vehicle geometry input 65
Fig. 4.12: Suspension properties input box 66
Fig. 4.13: Occupants & cargo input box 66
Fig. 4.14: Vehicle geometry input box 67
Fig. 4.15: Stability control input box 68
Fig. 4.16: Engine & drivetrain control box 68
Fig. 4.17: Tyre model general input box 69
Fig. 4.18: Linear tyre model control box 70
Fig. 4.19: 3D vehicle view 71
Fig. 4.20: Sequences control box 72
Fig. 4.21: Braking & acceleration control box 72
Fig. 4.22: Steering control box 73
Fig. 4.23: Implementation of paths to control vehicle (red line) 74
Fig. 4.24: Crash simulation control box 75
Fig. 4.25. Typical 2-vehicle impact schematic 76
Fig. 4.26: 2D view of multiple POIs (purple X) 77
Fig. 5.1 (i-viii): 2-Car Example 84
Fig. 5.2 (i-viii): Plymouth Low-Velocity Collision 86
Fig. 5.3 (i-x): Warnham High-Velocity Collision 89
Fig. 5.4 (i-xvi): Danbury Multi-Vehicle Collision 93
Fig. 5.5 (i-xx): Usk High-Speed Collision 98
Fig. 5.6 (i-xvii): Usk Multi-Vehicle Crash 105
Fig. 5.7 (i-xi): Coldra Junction Crash 111
Fig. 5.8 (i-ix): Rogliet Barrier Collision 116
Fig. 5.9 (i-ix): Coedkernew Rollover 121
Fig. 5.10 (i-xvi): Aberbeeg Bus & Car Collision 126
Fig. 6.1: RTA1 Example 134
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